Fetal cocaine exposure has been reported to have effects on newborn neurobehavior, sleep and state regulation, and EEG patterns. Early mother-infant interactions have also been shown to be disrupted among drug exposed dyads. Central nervous system development continues postnatally in humans and can be influenced by environmental factors such as maternal interactions. Maternal interactions facilitate the development of self regulation during the newborn period. The purpose of this study is to investigate central nervous system development in infants exposed to cocaine in utero and the contribution of variation in maternal interactions to this development. Both cardiac and electroencephalographic indices of CNS development are being assessed at conceptual ages of 40, 48, and 56 weeks. Mother-infant interactions are being observed at 48 and 56 weeks. Mothers and their infants are recruited from area full-term newborn nurseries based on toxicology and self reports of cocaine use during pregnancy. Newborns are tested for cardiac reactivity to an auditory stimulus while still in the nursery. Infant cardiac and sleep EEG are then assessed at the ARC at the specified follow-up ages. Mother-infant interactions are videotaped during a face-to-face play interaction and during a feeding. Additional assessments of infant reactivity and temperament as well as maternal psychopathology are collected by maternal questionnaire. Comparisons of cardiac vagal tone and heart rate, spectral components and patterns of sleep EEG, and sleep state distribution, between cocaine exposed and unexposed, full-term, SES matched infants will be conducted. These analyses will detect differences in CNS development during these infants' first 4 months and establish the contributions of both in utero cocaine exposure and maternal interactions.